Screen printing has hitherto been employed in an electronic component mounting process as a method for printing a substrate with paste, like cream solder and conductive paste. The method includes setting on a substrate a screen mask which has pattern holes aligned to locations of print targets and slidably moving a squeegee over the screen mask supplied with paste, thereby printing the substrate with the paste through the pattern holes. During screen printing, the paste supplied over the screen mask is scraped up with the squeegee, to thus be supplied over an entire print width of the substrate. During squeegeeing, the paste is scraped up in a direction of movement of the squeegee, being gradually shoved outside along a surface of the squeegee. Since the paste dislodged outside the width of the substrate stays behind without being scraped up by the squeegee and is susceptible to flection because an area of the screen mask located outside the width of the substrate is not supported from below, the paste acts as impediments to normal squeegeeing action.
In order to prevent occurrence of such a problem, a known screen printer (see; for instance Patent Document 1) has dam members that are provided on a squeegee while spaced apart from each other at a interval equal to a print width of a substrate and exhibits a function of preventing paste on a screen mask from being shoved outside the print width. According to the related art described in connection with the patent document, the dam members are pressed against the squeegee and the screen mask, thereby regulating effluence of the paste during squeegeeing operation.